Application of riluzole for promoting restoration following radiation

ABSTRACT

This invention relates to an application of riluzole or its pharmaceutically acceptable salts in the preparation of drugs having radiorestoring properties.

FIELD OF THE INVENTION

The present invention relates to a novel therapeutic application ofriluzole (6-trifluoro-methoxy-2-aminobenzothiazole) or thepharmaceutically acceptable salts of this compound.

BACKGROUND OF THE INVENTION

Riluzole is useful as an anticonvulsant, anxiolytic and hypnoticmedicinal product (Patent EP 50,551), in the treatment of schizophrenia(EP 305,276), in the treatment of sleep disorders and depression (EP305,277), in the treatment of cerebrovascular disorders and as ananaesthetic (EP 282,971).

DESCRIPTION OF THE INVENTION

It has now been found, surprisingly, that this compound may also be usedto promote restoration following radiation.

Restoration following radiation is useful in X-ray therapy, inparticular in the treatment of cancers, and against other sources ofharmful radiation such as those encountered by persons in areas in thevicinity of nuclear explosions.

EXAMPLES

The activity of the product has been demonstrated on the rhinencephalonof young rats subjected to an overall gamma irradiation.

Irradiation is performed by means of a gamma ray source, cobalt-60.

The animals used are 15-day-old male Sprague-Dawley strain rats weighing28 to 33 g, which are placed in an aerated Plexiglass restraining boxundergoing a rotation of 180° in order to carry out homogeneous overallirradiations in a single dose of 1.5 and 2.5 Gy, the dose rate of whichis 0.2 Gy per minute. The survival time between irradiation andsacrifice is 6 hours. All the animals are fixed by intra-aorticperfusion of a fixative fluid composed of 1% of paraformaldehyde, 1% ofglutaraldehyde and 0.05% of calcium chloride in 0.4M phosphate buffer,pH 7.3. To prevent coagulation, 0.04 ml of heparin is injected into theventricle, and 0.3 ml of 1% sodium nitrite to clear the vessels of redcells.

The animals are anaesthetized by intraperitoneal injection of 3%pentobarbitone sodium. The animals are then laid on their back and fixedto the operating table. The thoracic cage is opened and held open bymeans of 2 clamps. The heart is thus exposed, the tip of the leftventricle is incised and the perfusion cannula is introduced up to thebeginning of the arch of the aorta and clamped. The right atrium isincised and perfusion is performed. Inflow of the perfusion fluid iseffected under gravity. After perfusion, the animal's head is cut offand the brain is removed, immersed in fixative fluid and storedovernight at 4° C.

On the day following perfusion, frontal sections of the gyrus dentatusare cut under a binocular magnifier. The fragments collected areimmersed in the washing fluid for 5 minutes. They are then dehydrated inalcohol baths of increasing concentration and thereafter included inAraldite. 1-micrometer semi-thin sections are prepared using a Reichertultramicrotome with glass knives. They are stained in the heated statewith a filtered 1% solution of toluidine blue prepared in 1% boratebuffer, and then observed using an Orthoplan microscope.

The comparative study consists in counting on 3 non-serial sections(separated by 10 micrometers each) for each rat and on an aggregate of1000 cells (granular and subgranular) in total. The number of pyknoticcells is counted, and then the number of surviving cells observed inthis area. This enables the percentage of surviving cells relative tothe number of cells in the area to be calculated (percentagesurvival=100×living cells/living cells+pyknotic cells).

The product under study is administered intraperitoneally at doses of 1,2, 4 and 8 mg/kg, 20 minutes after irradiation (at the beginning ofpyknosis).

The results obtained are recorded in the following tables, and showthat, after treatment with the test product, neuronal degeneration isless than in irradiated controls not receiving a product.

                  TEST 1                                                          ______________________________________                                        IR-      CONTROLS        RILUZOLE (2 mg/kg)                                   RADIATION                                                                              CELLULAR SURVIVAL                                                                             CELLULAR SURVIVAL                                    ______________________________________                                        1.5 Gy   88.8%           91.2%                                                2.5 Gy   87.1%           92.2%                                                ______________________________________                                    

                                      TEST 2                                      __________________________________________________________________________                   RILUZOLE                                                                             RILUZOLE                                                                             RILUZOLE                                                                             RILUZOLE                                          CONTROLS                                                                             1 mg/kg                                                                              2 mg/kg                                                                              4 mg/kg                                                                              8 mg/kg                                           CELLULAR                                                                             CELLULAR                                                                             CELLULAR                                                                             CELLULAR                                                                             CELLULAR                                  IRRADIATION                                                                           SURVIVAL                                                                             SURVIVAL                                                                             SURVIVAL                                                                             SURVIVAL                                                                             SURVIVAL                                  __________________________________________________________________________    2.5 Gy  75.35 ± 2.4%                                                                      81.99 ± 2.32%                                                                     83.54 ± 1.96%                                                                     86.07 ± 2.78                                                                      85.41 ± 2.14%                          __________________________________________________________________________

As pharmaceutically acceptable salts, the addition salts with inorganicacids, such as hydrochloride, sulphate, nitrate or phosphate, or organicacids, such as acetate, propionate, succinate, oxalate, benzoate,fumarate, maleate, methanesulphonate, isethionate, theophyllineacetate,salicylate, phenolphthalinate or methylenebis(β-hydroxynaphthoate), orsubstitution derivatives of these derivatives, may be mentioned inparticular.

The medicinal products consist at least of riluzole, in free form or inthe form of an addition salt with a pharmaceutically acceptable acid, inthe pure state or in the form of a composition in which it is combinedwith any other pharmaceutically compatible product, which may be inertor physiologically active. The medicinal products according to theinvention may be employed orally or parenterally.

As solid compositions for oral administration, tablets, pills, powders(gelatin capsules, wafer capsules) or granules may be used. In thesecompositions, the active principle according to the invention is mixedwith one or more inert diluents such as starch, cellulose, sucrose,lactose or silica, under a stream of argon. These compositions can alsocomprise substances other than diluents, for example one or morelubricants such as magnesium stearate or talc, a colouring, a coating(dragees) or a varnish.

As liquid compositions for oral administration, pharmaceuticallyacceptable solutions, suspensions, emulsions, syrups and elixirs may beused, containing inert diluents such as water, ethanol, glycerol,vegetable oils or liquid paraffin. These compositions can comprisesubstances other than diluents, for example wetting, sweetening,thickening, flavouring or stabilizing products.

The sterile compositions for parenteral administration can preferably besolutions, aqueous or non-aqueous, suspensions or emulsions. As asolvent or vehicle, water, propylene glycol, a polyethylene glycol,vegetable oils, especially olive oil, injectable organic esters, forexample ethyl oleate, or other suitable organic solvents may beemployed. These compositions can also contain adjuvants, especiallywetting, tonicity, emulsifying, dispersing and stabilizing agents. Thesterilization may be carried out in several ways, for example by asepticfiltration, by incorporation of sterilizing agents in the composition,by irradiation or by heating. They may also be prepared in the form ofsterile solid compositions which can be dissolved at the time of use insterile water or any other sterile injectable medium.

The doses depend on the effect sought, the treatment period and theadministration route used; they are generally between 50 and 800 mg perday via the oral route for an adult, with single doses ranging from 25to 200 mg of active substance, and between 25 and 600 mg per day via theintravenous route for an adult, with single doses ranging from 12.5 to200 mg of active substance.

Generally speaking, the doctor will determine the appropriate dosage inaccordance with the age, the weight and all other factors specific tothe subject to be treated.

The examples which follow illustrate medicinal products according to theinvention:

EXAMPLE A

Tablets containing a 50 mg dose of active product and having thefollowing composition are prepared according to the usual technique:

    ______________________________________                                        Riluzole            50 mg                                                     Mannitol            64 mg                                                     Microcrystalline cellulose                                                                        50 mg                                                     Povidone excipient  12 mg                                                     Sodium carboxymethylstarch                                                                        16 mg                                                     Talc                 4 mg                                                     Magnesium stearate   2 mg                                                     Colloidal silica, anhydrous                                                                        2 mg                                                     Mixture of methylhydroxypropyl-                                               cellulose, polyethylene glycol                                                6000 and titanium dioxide                                                     (72:3.5:24.5)                                                                 q.s. 1 finished film-coated tablet                                            weighing 245 mg                                                               ______________________________________                                    

EXAMPLE B

Hard gelatin capsules containing a 50 mg dose of active product andhaving the following composition are prepared according to the usualtechnique:

    ______________________________________                                        Riluzole            50 mg                                                     Cellulose           18 mg                                                     Lactose             55 mg                                                     Colloidal silica     1 mg                                                     Sodium carboxymethylstarch                                                                        10 mg                                                     Talc                10 mg                                                     Magnesium stearate   1 mg                                                     ______________________________________                                    

EXAMPLE C

An injection containing 10 mg of active product and having the followingcomposition is prepared:

    ______________________________________                                        Riluzole              10     mg                                               Benzoic acid          80     mg                                               Benzyl alcohol        0.06   cm.sup.3                                         Sodium benzoate       80     mg                                               Ethanol, 95%          0.4    cm.sup.3                                         Sodium hydroxide      24     mg                                               Propylene glycol      1.6    cm.sup.3                                         Water                 q.s. 4 cm.sup.3                                         ______________________________________                                    

The invention also relates to the process for preparing medicinalproducts which can be used to promote restoration following radiation,consisting in mixing riluzole or the pharmaceutically acceptable saltsof this compound with one or more compatible and pharmaceuticallyacceptable diluents and/or adjuvants.

The invention also relates to a method for treating a mammal, and inparticular man, requiring restoration following radiation, comprisingthe administration of an effective amount of riluzole or thepharmaceutically acceptable salts of this compound.

Although the invention has been described in conjunction with specificembodiments, it is evident that many alternatives and variations will beapparent to those skilled in the art in light of the foregoingdescription. Accordingly, the invention is intended to embrace all ofthe alternatives and variations that fall within the spirit and scope ofthe appended claims. The above references are hereby incorporated byreference.

We claim:
 1. A method for promoting cellular restoration followingirradiation, said method comprising the step of administering to apatient in recognized need of such restorative treatment an amount ofriluzole or a pharmaceutically acceptable salt thereof effective forpromoting said cellular restoration following irradiation, wherein saidriluzole is administered to said patient after the patient has beenirradiated.
 2. A method according to claim 1, wherein riluzole isadministered orally at a dosage of 50 to 800 mg per day.
 3. A methodaccording to claim 1, wherein riluzole is administered intravenously ata dosage of 25 to 600 mg per day.
 4. A method according to claim 1,wherein said riluzole or said pharmaceutically acceptable salt thereofis mixed with at least one compatible and pharmaceutically acceptablediluent or adjuvant or both.